as the need of millions of uninsured Americans for healthcare.
Why?
One of several assumptions underlying the sandwich example is that two people meet, one with a sandwich and one without. The problem is that in a society of hundreds of millions of people which is in addition severely divided in every respect by a vast disparity between the economic status of rich and poor, that assumption does not apply because the rich, those with the healthcare sandwiches and poor, those without the healthcare sandwiches do not meet.
There are a number of other assumptions in the give me your sandwich analogy that do not work. For one thing, it assumes that the person with the sandwich is not hungrier than the person without one. That is not always the case. The point of the ACA is not to deprive a person of a sandwich when he needs it but to give each at least a basic sandwich when needed.
The logical outcome in a society in which people rely on generous people handing out sandwiches and greedy people taking the sandwiches would be that the greedy would amass so many sandwiches that the sandwiches would rot while the generous would give away their sandwiches and have nothing to eat.
In a sense, that is the status quo that the ACA is intended to cure.
While upper class ladies get their noses fixed, their lids and chins lifted and their breasts enlarged, many poor women cannot afford to visit a general practitioner when they have lumps in their breasts and finally go when it is too late.
The sandwich analogy does not work. The upper class ladies getting cosmetic surgery never run across the poor farmworker who needs to go to a doctor about that lump in her breast.
Obamacare, the ACA, gives each the very basic, barebones healthcare she needs. If the upper class lady wants more, she can still buy it for herself.
The ACA concept has worked since the 1960s in Medicare. I know a self-described "wealthy" woman who waited to get certain expensive care until she qualified for Medicare. You have a suspicious bump in your breast, you go to the doctor.
Medical care for the poor should not be left up to the kindness of strangers the poor will never meet.